The present invention relates to a new improved construction of control apparatus having frequency-dependent control elements, and furthermore, pertains to application of the control apparatus to regulating the steam pressure of boiling water reactors.
Control loops in which importance is laid on a particularly fast response require a high gain (cf. W. Oppelt: Kleines Handbuch technischer Regelvorgange, 2nd revised and enlarged edition, Weinheim 1956, p. 355 et seq.) In such control loops this can very easily give rise to unstable conditions. In order to prevent unstable control conditions of this nature, either the gain can be reduced (although this in turn leads to longer control times), or the control loop can include additional elements which have a low gain in the range of frequencies within which the control system is unstable.
Thus, in the above-mentioned book by W. Oppelt (p. 382 et seq.), for example, a control element is described which, in order to prevent unstable regulation, exhibits a gain which decreases linearly with increasing frequency.